RE: Manual J software
The biggest problem I’ve seen (beyond all the software being strictly windows based) is the cost of the software that looks like a middle schooler created it.
If you’re going to charge $500+ for software, that’s fine…. but at LEAST have it polished.
One issue I’ve seen with Carmelsoft is that it appeared to not deduct wall square footage when they contain windows. If it wasn’t that, there was some reason I stopped using it that I can’t recall.